Aspects of semiconductor technology has focused high-speed semiconductor devices having enhanced storage capacities for various applications. In order to obtain such qualities, enhanced integration, response speed and metal wiring processing of semiconductor devices has been developed.
Metal wiring processing may require the implementation of the paths of power supply and signal transfer constituting a circuit by interconnecting individual transistors in a semiconductor integrated circuit on and/or over silicon. A non-memory device has led the technique in this field.
The metal wiring layer of a semiconductor device may be formed of copper, tungsten, aluminum or any alloys thereof. The metal wiring layer may function as a contact with devices, an interconnection therebetween, and a connection between a chip and an external circuit, etc.
Integration of semiconductor devices has increased, and the size of metal wiring has become small so that the wiring can be formed by expanding the thickness of the metal wiring in order to secure the resistance of the metal wiring.
As illustrated in example FIG. 1, first Ti film 120 and first TiN film 130 may be deposited on and/or over lower insulating interlayer 110 of a semiconductor substrate provided with a predetermined lower structure using a sputtering method. Al film 140 can be formed on and/or over TiN film 130. Second Ti film 150 and second TiN film 160 can then be sequentially deposited.
Thereafter, a photoresist can be applied and patterned on and/or over second TiN film 160 to form a predetermined pattern. Thereafter, a dry etching process using the pattern can be performed on the Al wiring stacked structure including a multi-layer film formed of first Ti film 120 and first TiN film 130 formed under Al film 140, and second Ti film 150 and second TiN film 160 formed on and/or over Al film 140.
Upper dielectric interlayer 170 can be formed for insulating between the plurality of Al wiring stacked structure patterns formed using an etching process.
When depositing Al film 140 using a sputtering method, the temperature can be gradually increased in order to lower resistance and to reinforce electro migration (EM) characteristics by enlarging the size of the metal grain. Accordingly, a grain boundary can be enlarged to an extent that the size of the metal grain enlarges, and in particular, the recession of the grain boundary also enlarges at a triple point as the thickness of Al becomes thicker.
If a subsequent annealing process is performed in such a state, the Al moves along the grain boundary to form a hillock on the surface and grows in order to solve the stress due to the difference of thermal expansion coefficient between the Al and Si used as a semiconductor substrate.
In order to prevent such a phenomenon, Ti/Tin has been formed on and/or over the Al. The film capable of preventing a hillock phenomenon is TiN. However, if the TiN film is formed too thick, it may lower the resistance of the wiring. Therefore, there is a restriction on the expansion of the thickness of the TiN for preventing the hillock phenomenon.